1. Field of the Invention
The present invention relates to a fuel injection device, in which fuel in a fuel tank is increased in pressure by a motor-driven fuel pump, and the fuel increased in pressure is supplied toward a fuel injection valve.
2. Description of the Conventional Art
A conventional fuel supply device using a fuel pump is illustrated in FIG. 3.
In FIG. 3, T is a fuel tank storing fuel therein, and a fuel pump P is fixed and provided in the fuel tank T through a support member such as a stay or the like.
The fuel pump P is formed with a pump portion 51 and a motor portion 52 for rotating and driving the pump portion 51 in a housing 50. As for the pump portion 51, an impeller 54 is rotatably provided in a pump chamber 53, and a pump intake passage 55 is opened in the pump chamber 53.
Further, when the impeller 54 is rotated by rotating the motor portion 52, the fuel is increased in pressure in the pump chamber 53, the fuel sucked from the pump intake passage 55 into the pump chamber 53 passes through an outer circumference of the motor portion 52, and is supplied toward an fuel injection valve J from a pump discharge passage 56 opened on an upper end.
On the other hand, a relief valve R is provided at the fuel pump P. Here, an inner part and the outside of the housing 50 are connected with a relief passage 57 and the relief valve R is provided in a relief passage 57.
The relief valve R is necessary to prevent damaging of the fuel pipe and leaking of the fuel, when a fuel pipe on the downstream side is closed, in which the fuel pipe is connected from the pump discharge passage 56 to the fuel injection valve J. The relief valve R opens the relief passage 57 at a fuel pressure being more than a fixed pressure, discharges the fuel pressure in the fuel pipe toward into the fuel tank T, and prevents increasing of abnormal pressure in the fuel pipe.
As the fuel pump P is provided in the fuel tank T, such the fuel supply device is generally called as an in-tank type fuel supply device.